1. Field of the Invention
The present invention relates to a rotary tabletting press for production of tablets from tabletting material.
2. Description of the Related Art
In a conventional tabletting machine, powdered or granulated material to be tabletted is fed onto the surface of a rotating die table within the confines of a feeder so as to fill dies in the die table as a die table rotates underneath the feeder. Thus, the surface of the die table rotates largely in an environment of fresh air, whilst product is introduced to that surface locally by means of the feeder. The quantity of material delivered to the die cavity is determined by the position of the lower punch in the die cavity and the effect of the trailing edge of the feeder scraping across the upper opening of the die cavity thereby leaving a metered dose within the die cavity. Opposed pairs of vertically reciprocal punches operate to enter the dies from opposite ends and are operated by stationary cams. Means is provided for adjusting the cams in order to adjust the amount of material which is compressed in each die to form each tablet and to control the thickness of the resulting tablet. In the conventional die press the finished tablet is ejected upwardly through the upper opening of the die cavity by upward movement of the lower punch. Naturally, the upper punch is elevated to permit this.
With the known system it is inevitable that some tabletting material will escape the boundaries of the feeder onto the rotating die plate and hence into the tabletting enclosure. This is disadvantageous since it results in loss of tabletting material and prolongs the clean-down operation at the end of the tabletting run.
It is an aim of the present invention to overcome the above problems whilst utilising a tabletting cycle which conforms largely to conventional and proven principles.